Display screen or portion thereof with a graphical user interface



The FIGURE is a front view of a display screen or portion thereof with agraphical user interface showing my new design.

The broken line showing of the display screen or portion thereof formsno part of the claimed design. The broken line showing of text andlighter broken line showing of portions of the graphical user interfaceform no part of the claimed design.

CLAIM I claim the ornamental design for a display screen or portionthereof with a graphical user interface, as shown and described.